Help restoring from .tar archive

so, somehow i managed to mess up the installation of ubuntu 10.04 LTS i had. long story short, I've reformatted my boot drive and I've discovered that despite having many backups, the fact that i've reformatted means the UUID of the current partition to be restored does not match the UUID of the backed up partition.

ive tried doing a fresh install, to generate the grub files specific to the new partitions UUID, and overwriting those onto the backup after restoring. again, long story short, i've still yet to restore my OS.

ive also tried restoring and followling the guide here with regards to reformatting. i.e., manually setting the correct UUIDs in /etc/fstab and /boot/grub/grub.cfg (not /boot/grub/grub.lst becuase of the info here), and still nothing.

this really seems like it should just be a matter of restoring most files from my backup while keeping certain files from a "fresh" install becuase of the reformat, but I'm really at a loss as to what thos are. it also seems reasonable that i could restore certain parts of my backup onto a fresh install with similar effect.